Finishing cutter



K. B. KAISER FINISHING CUTTER Feb. 26, 1952 2 SHEETS-SHEET 1 OriginalFiled 001;. 5, 1945 karl B kafser Feb. 26, 1952 K. B. KAISER 2,586,955

FINISHING CUTTER Original Filed Oct. 5, 1945 2 SHEETS-SHEET 2 Qda I )3Wale/er Patented Feb. 26, 1952 Karl B. Kaiser,

Rockford, Ill., assignor to The Ingersoll Milling Machine Company,Rockford,

111., a corporation of Illinois Continuation of application Serial No.620,479,

October 5, 1945.

1950, Serial No. 155,410

' The general object is to provide a plural tooth face milling cutterwhich enables a work surface to be finished milled to greater flatnessthan has been possible with prior face milling cutters, which presentsto the work'a continuous cutting edge free from interruptions orcorners, which is simple in construction and convenient to sharpen withthe active portions ofcutting edges located precisely in a common plane.

. A more detailed object is to provide a face milling cutter of theabove character, the teeth of which have cutting faces convexly curvedabout the longitudinal axes of the teeth and intersecting flat primaryclearance faces at cutting edges whose projection on radial planes ofthe cutter through the tips of the respective teeth constitute theflattest portions of shallow ellipses.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a perspective view of a facemilling cutter embodying the present invention.

Figs. 2 and 3 are fragmentary cross-sectional views taken respectivelyalong circumferentially and radially extending lines through the cutterbody.

Fig. 4 is an enlarged view of a portion of Fig. 2.

Fig. 5 shows. the arrangement of the cutter teeth relative to aworkpiece during a face milling operation.

Fig. 6 is an end view of one of the cutter teeth.

In the drawings, the invention is shown for purposes of illustrationembodied in a finishing cutter of the face milling type comprising abody centrally apertured at 9 and having holes 8 for receiving screwsfor attaching the body rigidly to the rotary spindle of a millingmachine. A plurality of teeth I I projecting from one end surface l2 ofthe body are arranged therearound in an annular series for takingsuccessive .arcuate cuts across the workpiece I as the cutter whilerotating about its axis 6 in the direction shown by the curved arrow inFig, 5 is fed transaxially along the work in the direction of the otherarrow.

As shown, each tooth comprises the end portion of a solid cylinder l3received in a bore 14 in the body and clamped therein by screws IS. Theinner end of each cylindrical blade may be backed by a suitable abutmentl6 which may comprise the end of' a set screw I! carried by a plug [8which is threaded into the enlarged end of the bore opposite the toothproper.

The bores M are inclined in the cutter body at the angle desired toimpart the desired rake This application April 12,

1 Claim. (Cl. 29-105) 5 to the cutting face I9 on the forward or leadingside of the tooth. This face is of convex contour and is arcuatelycurved about an axis of curvature which extends longitudinally of thetooth and in.

tively narrow in the present instance and the remainder 24 of the toothend is disposed at a greater angle, for example, seven degrees, so as toconstitute a secondary clearance face. By regulating the magnitudes ofthe angles of the .pri-' mary and secondary clearance faces 20 and 24,both quality of finish and depth of stock may be varied to suit therequirements of any particular job.

By utilizing the convexly contoured side of the tooth as the cuttingface thereof and by making this contour truly arcuate, the intersectionof the cutting face l9 with the primary clearance face 20 is a curvedline 2| whose projection onto aradial plane 30 (Fig; 5) extendingthrough the leading tip or most advanced point 26 on the cutting edge isthe flattened side of an extremely shallow ellipse. Thus, the leading oractive portion of the cutting edge 2| including the tip 26 issubstantially fiat and then gradually curves away at 23 from thefinished work surface 22 thereby avoiding any interruptions or theformation of any sharp corners or projections along the active part ofthe. cutting edge. Because of this, the chip 25 removed by each toothdecreases progressively in thickness, and the flattened portion of theelliptical cutting edge merges so gradually into the plane of thefinished surface 22 that the latter possesses extreme smoothness. Inadidtion, the work surface is of uniform smoothness and extreme accuracyowing to the precision that may be obtained in sharpening the cuttingedges of the different teeth to identical contours with the tips 26disposed precisely in a single plane and equidistant from the body axis6. This involves simply the grinding of the flat primary clearance faces20 at the same angles on the different teeth, an operation which mayeasily be performed on modern cutter sharpening machines.

With tooth cutting faces which are convexly and arcuately curved aroundthe axes of the teeth, it will be apparent that the shear angle at whichthe cutting edge acts will vary progressively across the tooth face,increasing from a minimum at the initial point 26 of contact of thecutting edge with the finished work surface 22 which point is at thecenter of the primary clearance face 20. For this same reason, the shearangle may be varied as desired and the tip or initial point 26 of workcontact may be shifted around the tooth simply by tilting the plane ofthe clearance face 20 relative to the tooth axis. The initial point 26of work contact would be substantially at the center of the teeth withthe latter disposed as shown in Figs. 1 and 5 and each cutting edgewould intersect the work over an area a (Fig. 5).

The use of a convexly curved cutting face also results in more effectivedisposal of the chips. Since these flow along and off from a curvedsurface, they are warped and thus reinforced against curling so as tonaturally flow outwardly and out of interfering relation with respect tothe succeeding teeth.

Also, since the cutting edges 2| are rounded, it is unnecessary to grindthe cutter sons to match the cutting edge contour with the tilt of themachine tool spindle on which the cutter is to be used as is necessarywith conventional finishing cutters. The present cutter is thus adaptedfor use interchangeably in machines having different spindle tilts, andthis without regrinding of the cutter.

Owing to the variation in the effective shear angle across the cuttingfaces of the teeth, the improved cutter is much less susceptible tochattering than the cutters heretofore used.

In the use of the face milling cutter above described, the cutter bodyit] is attached to the rotary spindle of a milling machine, and theworkpiece is mounted for relative feeding of the work and rotatingcutter transaxially of the latter along the plane of the work surface tobe finished. With'the cutter rotating in the direction shown by thearrow in Fig. 1, and positioned for entry of the teeth to the properdepth in the work, the successive teeth will traverse arcuatepaths'across the work, the leading sides of the teeth presenting convexand arcuately curved cutting faces as described above. In

passing through the work, each individual edge would, in the absence offorward feeding of the work, remove metal and form an extremely shallowgroove of a cross section identical with the shallow portion of theprojected ellipse of intersection above referred to. By simultaneouslyfeeding the work in the direction indicated by the arrow in Fig. 5 as inany face milling operation, the grooves cut by the successive teethoverlap each other within the range of substantial flatness of thecutting edges. That is to say, the cutting edges 21 merge so graduallywith the finished work surface 22 as to leave the latter extremely fiatand smooth.

This application is a continuation of my copending application SerialNo. 620,479, filed October 5, 1945, and now abandoned.

I claim as my invention:

A milling cutter comprising a body adapted to be mounted on a spindlefor rotation about a central axis, a plurality of teeth projecting fromone end of said body along said axis and spaced angularly around andequidistant from the axis, each of said teeth, when said body is rotatedin the cutting direction about said axis, having a leading cutting faceconvexly curved about the longitudinal axis of the tooth, and a flatprimary clearance face on the end of each tooth lying in a single planeand intersecting said convex cutting face at a continuous graduallycurved cutting edge the projection of which on a radial plane of saidbody through the leading tip of the tooth is the flattest side of ashallow ellipse, the leading tips of all of said teeth being spacedequidistant from said body axis.

KARL B. KAISER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 77,522 Potter May 5, 18681,223,654 Allingham Apr. 24, 1917 2,348,089 Neikirk May 2, 19442,382,509 Seiter Aug. 14, 1945 2,413,452 Kaiser Dec. 31, 1946

